Numerical Investigation on Coastal Inundation of Storm Surges in Estuarine Wetland Waters

Zhang, H.; Zhang, M.; Shen, Y., and Xu, T., 2020. Numerical investigation on coastal inundation of storm surges in estuarine wetland waters. In: Malvarez, G. and Navas, F. (eds.), Proceedings from the International Coastal Symposium (ICS) 2020 (Seville, Spain). Journal of Coastal Research, Special Issue No. 95, pp. 1383-1388. Coconut Creek (Florida), ISSN 0749-0208.Coastal flooding caused by storm surges poses serious threats to coastal areas, communities and ecosystems. Plants that widely distributed in tidal flats play an important role in protecting the coastline from erosion, and mitigating extreme nature hazards. In this paper, based on the finite volume method (FVM), an explicit depth-averaged 2D model is established to investigate the interaction between salt marsh plants and storm surges in estuarine wetland waters. The Roe approximate Riemann solver, coupled with a drying-wetting boundary technique, is proposed in order to evaluate the effectiveness of interface fluxes for tracking the moving coastline and calculating storm surge land intrusions. The drag force induced by vegetation is added to momentum equations as an internal source to express the vegetation resistance to storm surges. The Jelesnianski 65 typhoon model is adopted to simulate the wind and pressure fields of the storm surges, and the background wind field is included in the total wind field. The proposed model is applied to investigate tidal levels, storm surges and flow currents during Typhoon Winnie and Typhoon Matsa in the Bohai Sea. Moreover, the model is used to explore the land intrusion and storm surge attenuation in Liao River Estuary (LRE) wetlands during Typhoon Winnie. Numerical predictions are found to match perfectly with those given by the measured data. The storm surge model can accurately reproduce the storm surge inundation process in wetland waters. The simulated results also indicate that salt marsh plants can reduce the flow current in vegetated regions, thus effectively attenuating the potential threats of storm surges.